mptcp: close TOCTOU race while computing rcv_wnd

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-63867
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-19 15:16:53 UTC
Updated2026-07-20 15:16:52 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: mptcp: close TOCTOU race while computing rcv_wnd The MPTCP output path access locklessly the MPTCP-level ack_seq in multiple times, using possibly different values for the data_ack in the DSS option and to compute the announced rcv wnd for the same packet. Refactor the cote to avoid inconsistencies which may confuse the peer. Also ensure that the MPTCP level rcv wnd is updated only when the egress packet actually contains a DSS ack.

Risk And Classification

Primary CVSS: v3.1 8.2 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

EPSS: 0.001610000 probability, percentile 0.056260000 (date 2026-07-20)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary8.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
3.1CNADECLARED8.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected fa3fe2b150316b294f2c662653501273ff25bba8 301a33fd590c408a05c5df800e0cc1e6a8a2f8f8 git Not specified
CNA Linux Linux affected fa3fe2b150316b294f2c662653501273ff25bba8 68364963e5baf03f16b4420292291f75c8f66497 git Not specified
CNA Linux Linux affected fa3fe2b150316b294f2c662653501273ff25bba8 907ac6b1658e0277f979fcdfae2a753b495c1510 git Not specified
CNA Linux Linux affected fa3fe2b150316b294f2c662653501273ff25bba8 c4f4cf60797974873dbc8e100144682a6f2f861f git Not specified
CNA Linux Linux affected fa3fe2b150316b294f2c662653501273ff25bba8 3b8cbba7c0ed31189c89f90be247b8973ffa79ef git Not specified
CNA Linux Linux affected fa3fe2b150316b294f2c662653501273ff25bba8 8f4f0a157e8436a05bf8c3670b24dbc258911c43 git Not specified
CNA Linux Linux affected fa3fe2b150316b294f2c662653501273ff25bba8 8ab24fdebc369c0dfb90f82c1650b1e66662bb45 git Not specified
CNA Linux Linux affected 5.11 Not specified
CNA Linux Linux unaffected 5.11 semver Not specified
CNA Linux Linux unaffected 5.15.210 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.176 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.143 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.94 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.36 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.13 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/8f4f0a157e8436a05bf8c3670b24dbc258911c43 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/301a33fd590c408a05c5df800e0cc1e6a8a2f8f8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3b8cbba7c0ed31189c89f90be247b8973ffa79ef 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/68364963e5baf03f16b4420292291f75c8f66497 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/907ac6b1658e0277f979fcdfae2a753b495c1510 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8ab24fdebc369c0dfb90f82c1650b1e66662bb45 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c4f4cf60797974873dbc8e100144682a6f2f861f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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